Aerophone.



Lt DE FOREST,

AERoPHoNE. APPLICATION FILED DEU. 22,1905.

PATBNTBD Nov. 13, 1905.

UNITED STATES lPATENT orrren. L EE DE FOREST, orNEvf-YQRK, N. Y.'

AEBOPHONE.

Original application filed December 11,

To dll. whom it may concern,.-

Beit known that I, Lim DE FonEsT, a citizen of the United States, and aresident of New York, in the' county of New York'and State of New York,have invented a new and usefulImprovement in Aerophones, of which thefollowing is a s eciiication My inventionre ates to wireless-telephonesystems for transmitting and receiving vocal or other sounds, includingarticulate speech, b'y electromagnetic waves.

The object of my invention is to produce a- Wireless telephone or aerohone in which a 'resistance device is varied Iby and in accordance withthe air vibrations accompanying vocal or other sounds, and therebycorrespondingly varies the amplitude of continuouslyftransmitted trainsof electroma netic waves and in which said waves so varie as toamplitude develop in a receiving system elecltrical oscillationscorrespondingly and thereby correspondingly vary the amplitude of thecurrent in a tele hone-receiver.

My invention may best ecunderstood by having referencev to the drawln''4iwhich 'accompany and form a par-t of this specification and whichillustrate conventionally several devices and systems of circuitswhereby myl invention may be lcarried into effect.

In the drawings7 Figures 1, 2, 3, and 4-'are diagrams of aerophonetransmitting systems.

In Figs. l, 2, and 3, G is a high-frequency alternatmg-current generatorproducing at leastl seven hundred and fifty cyclos per sec#V ond, andpreferably the frequency of said enerator should be as 'high as canconven-A iently and commercially be produced.

In Fi 1 and 3 the enerator G energizes lthe osciating ci'rcuitC glidirectly, although,

' interposed between said circuit and generatorfor appropriately varyingth diflerence of .potentialgimpressed upon the conde ser C b thegenerator. By means of the .adjustable connectionsoflthe oscillatingcircuit and vantenna A with vthe inductance L the natural eriods oftaught into-a The elenientshown in the several 'ig'ures, 'naliKi'Kf's-K'', re resents a resistancefdea hablen aracter whiclris'adatbeeontrolled by the vibrationsof't' e greement.

Specification of Letters Patent.

1905, Serial No. 291,222. Divided and this application filed December22, 1905.

Serial No. 292,922,

In Fig. 1, K is re is an arc of the type investigated by varied,

"of the antenna.

i in Fi s. 1,2, and 3,is preferred, l do not linut resistance device ortransmit'termay .be so as shown in Fig. 2, the transformer I may bev Ido not limit myse to any particular vari- 'sai l1 antenna and circuitmay be Patented Nov 13,1906.

resented as a carbon mcrophone, preferab y of the kind used in circuitscarrying currents of am litudes large com ared to the amplitudes o thecurrents4 whidli are-modified by the usual granular car# bon transmitterin ordinarywire telephony. 6o

' In Fig. 2, K is a ilame made more conductingby the addition of sodiumsalts or other suitable salts.

In FigB, K is a spark-gap. In Fig. 4, K" Simon (Wiedemanns Annalen, Vol.64, p. 233, 1898) and Duddell (Journal of the Institution of ElectricalEngineers, December 13, 1960, p. 232) and known as the speaking-arc.

The variableresistance devices may bestbe placed, as shown in Figs. 1,2, and 3, at points in the system near the earth connection, because atsuch points the current in the system is near its maximum value and .theotential "s near its minimum value. Accor ingly the said resistancedevices are lessliable to be injured or rendered inoperative by havingexcessive potentials impressed upon their. terminals and are enabled ltopro- 'duce a far greater variation in the amplitude 8o of the currentsin the antenna, and hence in' the amplitudoi tlieradiated waves, byslight changes in resistance than Iif they were located between theinductance l, and the top While the location of the Vvariable-resistance devices in the. antenna system' near the earth connection,as shown -myse f to a variable-resistance transmitter so located, lfor,as shown at IC" in Fig. 4, said 9o located as to be common to theantenna and the closed oscillatin circuit. In other words,

able-resistance transmitter or to any particular location or positionthereof in the system, but consider an suitable transmitter o erativelyassociate with the system, as set orth in the claims, within. the scopeof my invention when used to vary'the .am litude of elec? 1 eo Si?slrquema .vif the maw com an -'s. 'ee hun reg-pun sallions pe With'all'the-'varr any s11itable. so n trating may be used-such, for ex#rainple, as the megaphone M5 (shown in Figs.

2, 3, and 4) or-the Well-known compressed-air device F (shown in Fig.3), in which the diaphragm V of the megaphone operates on a reducin-valve to vary the tan vF through the nozzle G.

The operation is as follows: In Figs. 1, 2, and 3 the'genera'tors Gcharge the condensers C a suilicient number of times per second to-create inthe oscillating circuits S C L electrical'oscillations havinga spark frequency higher than the more essential frequencies vwhich makeup the complex voice-waves, andsaid oscillations result inthe radiationfrom the antenna of electromagnetic Waves having similar sparkfrequency. The electrom'agnetic Waves develo oscillations in a receivingantenna, there y -producing a frequency 'oft e transmitted Waves.

current varyin at a rate'equal to thespiak e effect of said varyingcurrent on the telephonereceiver depen rate of its variation.

" speaking-arc circuits of higher than the most important frequenciesloccurring. in telephonie transmission, in

'which'case the telephonewill produce anote j having .the pitch e ualto` the spark4 fre# guency employed at t 0i'. the currents in the localtelephone-circuit .will produce a correspondin variation in thesoundlfemitted by the telep one', and therecreatesin its circuit C L Kelectrical'osv cillations the .frequency of Whichmaybe vf Qre- .if byany of thev variable-resistance transmitters. shown herein or by anyother means the am litude ofy the transmitted wavesbe modi ed in-amanner .correspond- `ing to the voice- Waves the telephone will reat thetransmitting'fstation.

produce sounds simulating those produced In Fig.. 4 the direct-currentgenerator'G- regulatedin the Well-known manner lby regu:

voice.-wavegxconcentratedv M, which is directed toward the ksarol KC,-

latingthe electrostatic time constant of the condenserfcharging,circuit,In Fig. 4-the by the megaphone producethefdesired current variationsinthe and in accoi'dance withspeech-Waves the the ilow of air from ofcourse, u on thel e transmitting-station. n either case any variation inthe amplitude' amplitude of continuuslyftransmittedtrains of waveshaving a spark-.gap frequency higher than the more essentia fre uenciesaccompanying speech', -and therefore do `not wisinto limit my inventionto the particular embodiments thereof herein shownA and described.

1. An aerophone comprising means for continuously transmitting trains ofelectromagneticetherwaves having a spark t'i'equency higher than-themore essential -frequencies accompanying speech-Waves, and means locatedin the antenna system between the earth connection thereof and the pointat which energy is supplied thereto whereby said Waves may be modifiedin accordance with speech-waves.

2. In an aerophone, an oscillating circuit including a condenser and aspark-gap,

circuit electrical oscillations havinga spark frequency higher' than themore essential frequencies accompanying speech-waves and means locatedin't e antenna Systembet'ween the-earth'Tconnection thereof' and thepoint at which energy is supplied' thereto, whereby 'said waves may bemodified in accordance with s @ech-Waves.

quencies accompanying speech-waves, and a tem between the earth-connecti'onthereof and the oint at which energy is sup lied thereto Wereby said waves may be modi in accordancefwitli speech-Waves. A

4. In an aeroplione, an oscillating circuit frequencies accompanyingspeechlwaves and a resistance' devicel locatedl in the antenna systembetween the earthconnection thereof and the `point at which' energy is`supplied ,theretofwhereby said oscillations maymodified in accordancewith speedy-Waves;

` thereof and the '0in-trat which energy! is sup; fplied4 thereto W andmeans for converting'said oscillationsso modiied'into electroradiantenergy-."]

anta'erophone, means foiv dvel" in electrical o'scllationshaving arelatively 'g connection 'thereof and the L energyis vsupplied .theretoW ereby said 'osae'rop one comprising ineai i s j f or continuouslytransmitting trains of` electro"-4 magnetic eth er lWaves having a sparkfrequency higher than the more essential `fre^ resistance device located1n the antenna sysfied including a condenser and a spark-gap. means forcontinuously 'developing 'iii` said circuit electricaloscillations'having a 'spark' =a* resistance-d evice'locatcd 1n.' the-v.antenna-:system betweenthe' earth oint at which ,85 means forcontinuously developing in said iol lof

frequency higher than ythe more l,essential H5 5. In an aerophone, meansfor devel'o'iii 'electrical oscillationshavingarelativel f' 'g spark.frequencyymeans located in -`tli'e aritenna-:system "between the earthconriectinjl no ereby.said oscillations lly e modified in MaccordanceWithsoi'ndjwa'ves, v

soundwaves,and means for converting said nection' thereof and the ergyissuppledthereto f 'tenna,'me'ans"for developingel'ectrical oscilla- Itenna having a de for impressing thereon electric :the Sam@ and havingaspark energy; ,j

7. 1 nml-ae tenna means for' located between: the earthconnectionthereof nectionl thereof and the orgy iS, 4Supplied thereto 'saidgap tothe oscillations passing, across it,

ciLlatiensmay oscillations s into electroradiant'` gaat;staatsgevel'oping electrical oscillations therein, meansin said antennaand thereto* whereby said "oscillations may be 8 In an -aerepho e;transmitting 811- tenna, means .for developing electrical oscillationstherein ,and meansin saidantenna and*- located between-the earthconnection thereof and the point at whichenergy supplied varied inaccordance with vocalvsounds.

9. In an -aerehonegA a transmittingantenna, means for evelopingelectrical oscillations therein, anda resistance device in said antennaandlocated between' the earth con- ]laloint- -at which en.` w ei'ebysaid oscillations may evaried,

10. In an aerophone, a transmitting-antion's''therein, anda reslstancedevice .in said antenna andlocated .between the earth conloiit at whicheny i w tions: may be modified in accordance 'with vocalsoun tls'.

1 1. In an aerophone, means for developing electrical oscillations aspark-gap located in the path of said ose' ations, a source Ofcom--pressed gas for modifyingthe resistance of and means `dontrolled byvoice-waves for controlljn the effect of said compressed gas on the'resistance of said gap. y

12., In an aero hone; a transmitting-an- 'te natural period, means aloscillations I- ssao'lys ffre'qaaey higher, than the means in said,antenna an the earth connection thereof and the point 'at yresistancedevice antenna and ated with said sparkereby saidvoscillaquenciesfaccompanymg s leech-Waves, and .located between whichenergy is lsup lied thereto whereb said oscillations maylb ancewithspeech-waves." 413. Inan aero hone, a4 transmitting-amtenne. having a de'te natural period means for impressing thereon electrical osc' lationshaving the sameperiodl and having a spprrk' frequencyrhgher than themore essentia quencies accompanyin speech-waves and a l located betweenthe earth connection thereof and the point at which energy is suppliedthereto whereby said oscillations may e modified in accordance withspeech-waves.' l l 14. In an aerophone, a transmitting-an'-- tennahaving a 4definite natural period,- means for impressing thereonelectrical os-lcillations having the same riod and having a sparkfrequency higher than waves, aA resist-ance deviceonsistien of a in thesparkap of constant length arrang more,V essential e modifiedin accor A,

sls-

the more es- -sential frequencies accompanying speech- I` ath o saidoscillations, and means associ-1 lations may b e m in accordance withsp'ee ch-waves 1'5 HIn" `an aerophone, al transmitting-anan'tenna-belowsaid means whereby the' oscilwhereby said scilvtenna, anoscillation-circuit, ine o era-A tively associating said circuit with aian 'tenna, and a resistance device located in said lationsin saidantenna maybe modified in' 4 accordance with vocal sounds.-

In testimony whereof I have hereunto subscribed my name this 18th day ofDecember, .1905.. c DE FOREST.

M. M Mmnm- Pirna? FAnNswon'rH.

